Machinable titanium base tellurium alloy



Patented Feb. 2, 1954 Harry P. Croiit, Greens Fa Kennecott N. Y., acorporationof No Drawing, Application May 20', 1952," Serial No. 289.005

2 Claims.

This invention relates to titani m-base alloys and, more particularly,to titanium-base alloys characterized by good machining properties.

In the past, little has been known concerning the machinability oftitanium metal and, consequently, there is practically no informationrelative to machinable alloys of titanium. Separate publications havecompared the machinability of titanium to that of stainless steel, inone instance, and to that of free-machining stainless steel in anotherinstance. since the machinability of stainless steel and free-machiningstainless steel difier by a factor of about two, it will be apparentthat the actual machinability of titanium metal is a somewhatcontroversial subject. In view of recent interest in titanium alloys andtheir applications, it has become increasingly desirable thatinformation relative to the machinability of titanium alloys be obtainedand that titanium alloys having good machining properties be developed.

It is, therefore, an object of this invention to provide alloys oftitanium which are readily machinable.

It is a further object of this invention to provide free-machiningalloys of titanium comprising titanium and an element having lowsolubility in titanium.

Yet another object of this invention is to provide free-machining alloyscomprising titanium and tellurium.

Other objects and advantages of this invention will be apparent, in viewof the following detailed description thereof:

In general, this invention relates to free-machining titanium-basealloys comprising titanium, and from about 0.02% to about 0.45%tellurium, particularly alloys containing from 0.05% to0.40% tellurium.

The introduction of tellurium as an alloying element in titaniumpresents substantial difiiculty because of the low boiling point andhigh vapor pressure of tellurium. For this reason, it is desirable toform a master alloy of titanium and tellurium to provide a relativelyhigh-boiling point compound for subsequent addition to perature range offrom 950 1 to 1000 F., the tellurium reacts exothermally with the tirms,Conn.,-assignorto Copper Corporation,

New York New York,

taniumproducing compounds having a metallic appearance. These compounds,or master alloys, may then be used in preparing titanium-lickluriumalloys of any desired composition.

'Ii-Te alloys of the present invention have been prepared and evaluatedfor machinability with results as tabulated in Table I below. Two commontypes of machining operations have been used in evaluating the machiningproperties of the present alloys. These two operations,

turning on a lathe and cutting with a saw, arebelieved to berepresentative machining operations and to afford a reasonableevaluation of relative machinability. Data I are reported on the basisof the machinability of unalloyed titanium as a reference. A value Avg.feed on alloy Index- 100X Av feed on standard Table I OompositiomPercent Te i gg fi gg 1 Balance titanium.

Lathe tests reported above were made on a glnalloyed attendant loss ofmechanical properties. Table II below shows that mechanicalproperditions of this invention:

Table II Ultimate 0.2Percent Elonge- Reduc- Vickers gggfi s'laensigiJStYieldth tion, Pcralign of Hardreng reng cent in tea ness Percent Te p.s. i. p. s. i. l-inch Percent Number Unalloyed- 75, 400 54, 300 29 51183 0.07 so, 600 66, 000 30 55 201 83, 200 64, 000 29 45 204 79, 200 60,000 27 45 190 78, 600 54, 500 28 44 203 1 Balance essentially alltitanium.

From Table II it is clear that the alloys of this invention possessincreased tensile strength and yield strength, as compared withunalloyed titanium, and. retain excellent ductility properties withoutsacrifice of hardness.

It will be clear that useful alloys with increased properties ofmachinability and good machinability and good mechanical properties havebeen disclosed herein. It will be understood that the particularproperties and descriptions are not intended to limit the scope of theinvention but are presented for illustrative purposes only. The

titanium used in preparing the alloys of the present invention may beproduced by either the magnesium-reduction method or by the iodideprocess, or in any other way, and may contain small amounts ofimpurities, such as carbon, iron, and nitrogen.

What is claimed is:

l. A titanium-base alloy consisting essentially of from .02% to .45%tellurium, balance titanium, characterized by an improved machinabilityof at least 104 as determined by a lathe test as compared with for anunalloyed titanium specimen.

2. A titanium-base alloy consisting essentially of from .05% to .40%tellurium, balance titanium, characterized by an improved machinabilityof at least 104 as determined by a lathe test as compared with 100 foran unalloyed titanium specimen. HARRY P. CROFT.

References Cited in the file of this patent Goldhofi, R. M., et a1.:TheInfluence of Insoluble Phases on Machinability of Titanium, publishedas ASM Preprint #30, 1952.

1. A TITANIUM-BASE ALLOY CONSISTING ESSENTIALLY OF FROM .02% TO .45%TELLURIUM, BALANCE TITANIUM, CHARACTERIZED BY AN IMPROVED MACHINABILITYOF AT LEAST 104 AS DETERMINED BY A LATHE TEST AS COMPARED WITH 100 FORAN UNALLOYED TITANIUM SPECIMEN.